night-blindness

As the retinal component of rhodopsin is derived from vitamin A, a deficiency of vitamin A causes a deficit in the pigment needed by rod cells. Consequently, fewer rod cells are able to sufficiently respond in darker conditions, and as the cone cells are poorly adapted for sight in the dark, blindness can result. This is night-blindness.

Strand of human hair

The diameter of human hair varies from 17 to 180 micrometers (0.00067 to 0.0071 in) 

food preservation

Many processes designed to preserve food will involve a number of food preservation methods. Preserving fruit, by turning it into jam, for example, involves boiling (to reduce the fruit’s moisture content and to kill bacteria, yeasts, etc.), sugaring (to prevent their re-growth) and sealing within an airtight jar (to prevent recontamination). There are many traditional methods of preserving food that limit the energy inputs and reduce carbon footprint.

Retina

The retina is a layered structure with several layers of neurons interconnected by synapses. The only neurons that are directly sensitive to light are the photoreceptor cells. These are mainly of two types: the rods and cones. Rods function mainly in dim light and provide black-and-white vision, while cones support daytime vision and the perception of color. 

Function of kidneys

The kidneys receive blood from the renal arteries, left and right, which branch directly from the abdominal aorta. Despite their relatively small size, the kidneys receive approximately 20% of the cardiac output.

Selections

A chart showing three types of selection. 1. Disruptive selection 2. Stabilizing selection 3. Directional selection

Mutation

Mutation followed by natural selection, results in a population with darker colouration.

DNA structure

DNA structure. Bases are in the centre, surrounded by phosphate–sugar chains in a double helix.

inspiring spider

Nephila pilipes is a species of golden orb-web spider. It can be found in Japan, China, Vietnam, Cambodia, Taiwan, Singapore, Myanmar, Indonesia, Thailand, Sri Lanka, India, and Papua New Guinea. It is usually found in primary and secondary forests and greeneries. Body size of female is 30–50 mm (overall size up to 20 cm), with males growing to 5–6 mm. It is one of the biggest spiders in the world.

Albino Mamba Snake